HomeMy WebLinkAboutNC0074756_Tox Sampling Report_20220810 (2)
August 10, 2022
MEMORANDUM
To: Corey Basinger
Water Quality Regional Operations, MRO
Through: Cindy A. Moore
Supervisor, Aquatic Toxicology Branch (ATB)
From: Madison E. Myers
Environmental Specialist I, Aquatic Toxicology Branch (ATB)
Subject: Whole effluent toxicity test results
Greater Badin Water & Sewer District
NPDES Permit # NC0074756/001
Stanly County
The aquatic toxicity test using flow-proportional composite samples of effluent discharged from
the Greater Badin Water & Sewer District has been completed. Greater Badin Water & Sewer
District has a permitted effluent discharge of 0.2 million gallons per day (MGD) entering Little
Mountain Creek (7Q10 of 41.0 CFS). Whole effluent samples were collected on July 19 and July
21 by Roberto Scheller for use in a chronic Ceriodaphnia dubia pass-fail toxicity test. The test
failed. Toxicity test information follows.
Test Type 3-Brood Ceriodaphnia dubia chronic pass-fail
Test Result Fail
Test Concentrations 83.4%
Control Survival 91.67%
Control Mean Reproduction 31.42 neonates
Test Treatment Survival 0%
Treatment Mean Reproduction 0.0 neonates
First Sample pH 6.91 SU
First Sample Conductivity 249 micromhos/cm
First Sample Total Residual Chlorine <0.1 mg/L
Second Sample pH 6.85 SU
Second Sample Conductivity 262 micromhos/cm
Second Sample Total Residual Chlorine <0.1 mg/L
Test results for the above samples indicate that the effluent would be predicted to have water
quality impacts. These samples were split and tested by Meritech. The chronic Ceriodaphnia
dubia pass/fail test performed by Meritech resulted in a pass. After reviewing the toxicity test
documentation from both ATB lab and Meritech, Inc. lab, we see no obvious reason for the
disagreeing lab results. ATB ended their monthly synthetic water Reference Toxicant Test on
July 13, which did not indicate any issues with the in-house culture health. We had a discussion
with the Regional Office staff member, Roberto Scheller. Each sample bottle was poured all at
one time. We discussed doing another test next quarter; being sure to mix the effluent well and
add 1/3 sample to each bottle and continue the well-mixed pour process until all bottles are
filled. This would be a way to ensure each bottle receives the same level of effluent. Please
DocuSign Envelope ID: 6FBE86BD-12AF-4369-B00F-BF5A0452F378
contact us if you have any questions or if further effluent toxicity monitoring is desired. We may
be reached at cindy.a.moore@ncdenr.gov and madison.myers@ncdenr.gov.
Basin: Yadkin-Pee Dee
cc: Roberto Scheller (MRO)
DocuSign Envelope ID: 6FBE86BD-12AF-4369-B00F-BF5A0452F378